The use of either free fatty acid or of filler, individually, in a fatty acid soap bar is known in the art.
Thus, for example, free fatty acid has been used in soap bar compositions. The addition of such free fatty acid is known as “superfatting” and superfat may be used to make a bar with enhanced user properties like enhanced lather and/or bar feel. However, it is known that, if too much free fatty acid is used in the bar, the bar may be too soft for structuring purposes such that a bar may not be processed at all and, if it is, may be extremely soft. In typical soap bars, the ratio of free fatty acid to total fatty matter (TFM) is not greater than 0.06. TFM is combination of free fatty acid and fatty acid soap.
The use of filler materials (e.g., organic particles, polymers, wax, sugar, etc.) in soap bar compositions is also known. The use of too much filler is also generally considered undesirable because high filler can cause loss of bar integrity (crumbly bars). Again, it is typically found that the ratio of filler to TFM in a soap bar is not greater than 0.2.
Thus, if either filler or free fatty acid (FFA) alone is used in excess (very high ratios compared to soap), this can be very detrimental to processing and/or bar properties.
Unexpectedly, however, applicants have found that when high ratios of free fatty acid and of filler are used simultaneously, the use of one cancels out the deficiencies of the other such that, synergistically, they create a better overall bar. Thus, for example, the high degree of softness that would normally be expected from using high ratio of FFA to TFM is firmed up by the filler which is used. Moreover, the filler can now be used in higher ratios without affecting bar integrity because it is compensating for the softness caused by the free fatty acid; and, at the same time, the filler brings sensory benefits (e.g., creamier lather).
U.S. Pat. No. 3,576,749 to Megson discloses a soap bar with 2 to 15% free fatty acid. There is no disclosure of what happens to bar properties (e.g., increased softness) if free fatty acid is used in high amounts (for example at above 10%) and where there is no filler to compensate for such softness. In general, there is no disclosure of the combination of free fatty acid and filler, both used at in defined minimum ratios claimed in the subject invention, or of the synergistic effect unexpectedly allowing both to be used in such high amounts.
U.S. Patent Application Publication 2002/0045555 discloses bars containing talc and fatty acid. Again, however, there is no teaching or disclosure that levels of filler (e.g. talc) and free fatty acid (defined as ratio to total soap) can be high; nor is there a disclosure that there is an advantage (e.g., enhancing both foaming and tactile sensory properties) in doing so.
Unexpectedly, applicants have now found that the filler and free fatty acid can be combined in specifically claimed ratios relative to soap to obtain advantages.